Conventional power supply devices for lighting equipment using an LED (hereinafter referred to as LED lamps) include insulated power supplies using a transformer and non-insulated power supplies using no transformer. Among them, an invention related to an insulated lighting power supply device is disclosed in Patent Document 1, and an invention related to a non-insulated lighting power supply device is disclosed in Patent Document 2, both of which are power supply devices based on switching control.
The control of the lighting power supply device disclosed in Patent Document 2 is such that it supplies a predetermined output current based on the voltage divided from an input voltage by means of a series resistor and the voltage generated by current-to-voltage conversion of a sense resistor connected in series with a switching transistor. Further, dimming control is achieved by using a phase-controlling dimmer.